Schizophrenia and Post-traumatic stress disorder (PTSD) are not uncommon in the population and are major sources of disability and suffering. However, little is known of their biological basis. The main goal of this project is to study people with a history of schizophrenia or PTSD and people without a history of these syndromes in order to learn more about the biological basis of schizophrenia and PTSD. In addition, this population is being studied in order to comprehend the relationship between behavior and anatomical brain asymmetries measured on magnetic resonance imaging scans of the head